Make the cake: Heat the oven to 350 degrees. Lightly oil a 9-inch springform pan and line the bottom with parchment paper.

Whisk flour, cinnamon, baking powder, nutmeg, salt and baking soda in a medium bowl to remove any lumps.

Using a stand mixer with a paddle attachment (or electric hand mixer) on high speed, beat the sugar and eggs until very pale and thick and the mixture forms ribbons back on itself when lifted, 3 to 4 minutes. (This may take longer if using a hand mixer.) Add the pumpkin purée in two batches, beating on low until combined.

With the mixer still on low, gradually stream in the oil, then beat in the vanilla. The batter should look a little thicker.

Working in two batches, add the dry ingredients and mix on low speed, stopping and scraping down sides in between, until no streaks remain. Scrape the batter into the prepared pan and smooth the top. Bake until the top is firm and a tester inserted into the center comes out clean, 40 to 50 minutes.

Let the cake cool in the pan on a wire rack for 15 minutes, then run a knife around the edge and release. Cool completely for at least 1 hour before serving. (If working ahead, wrap the cake entirely in plastic and store at room temperature for up to 3 days, until ready to serve.)

Just before serving, make the whipped cream: Use a stand mixer with the whisk attachment, hand mixer or just a plain whisk (yes!) to beat the heavy cream until you reach soft, floppy peaks. Add the sour cream, maple syrup and a pinch of kosher salt and whisk to nearly stiff peaks.

Using a rubber spatula, plop the cream onto the cooled cake and spread it out, keeping some swoops and waves. Drizzle with more maple syrup and finish with flaky salt, if you like, just before serving.